Conference Agenda

Evaluating potential Carbon Capture and Storage (CCS) sites requires a standardized, multi-tiered screening approach to identify suitable and valuable storage assets. The workflow integrates both technical and non-technical criteria, which may partially conflict with one another. The technical criteria comprise Capacity, Geological Probability of Success (GPOS), and Data Confidence, while key non-technical aspects include e.g. economics such as proximity to infrastructure and major CO₂ emitters.

Capacity assessment is performed using probabilistic resource calculations, typically based on Monte Carlo simulations with predefined uncertainty distributions. The workflow includes Gross Rock Volume (GRV) definition, reservoir parameter characterization (including storage-efficiency factors), and pressure, temperature, phase and density evaluations. Uncertainties are assigned throughout the workflow, enabling the calculation of probabilistic storage estimates such as P90, P50, P10, and mean values.

The GPOS assessment comprises reservoir, seal, and containment characteristics. Reservoir evaluation considers the presence, continuity, thickness, porosity, and permeability of the target formations. Seal assessment focuses on caprock properties, sealing efficiency, and potential leakage pathways such as faults or fractures, while containment analysis additionally addresses structural and areal configuration. To account for variations in data availability and quality, the workflow incorporates a dedicated data-confidence matrix that reduces and homogenizes data-driven bias. The resulting confidence values are integrated into the GPOS assessment to derive an overall ranking parameter for site comparison.

Presented here is an onshore CCS screening conducted across different regions of Germany. The applied methodology demonstrates that a structured and standardized workflow can significantly accelerate the screening process while delivering robust, decision-supporting results.

Baden-Württemberg has set a goal to achieve climate neutrality by 2040, 5 years earlier than the Federal Republic of Germany and 10 years earlier than the European Union. However, Baden-Württemberg is home to large industry sites. This goal cannot be achieved without CO₂ capture and underground storage (CCS), if the industry is set to remain operational. Therefore, in this study we are focusing on Baden-Württemberg, to assess potential geological storage sites and barrier complexes, located in the Upper Rhine Graben and Molasse Basin. Furthermore, we take into account the current and planned pipeline routes for CO₂ transport, and the locations of the verified industrial emitters (119 plants) of Baden-Württemberg. With this dataset we were able to calculate the approximate required transport distance between the emitters, pipelines and possible storage locations. Furthermore, an evaluation of potential storage volumes with updated calculations based on Monte-Carlo-Simulations, fills some data gaps, especially in the Tertiary sequence of the Upper Rhine Graben already hosting gas storage sites and former hydrocarbon fields. The overall geopotential for CO₂ storage in Baden-Württemberg ranges from 582 Mt to 2500 Mt (P90 to P50). According to a conservative assumption (P90), the reservoirs in Baden-Württemberg may host 97 years of current CO₂ emissions from cement clinkers and lime-stone extraction. This data might help to estimate the maximum potential for CCS including transport for the main emitters in Baden-Württemberg, but will have to be adjusted for individual structures.

The geological storage of CO₂ in mafic rocks depends on efficient mineral carbonation, yet the role of iron-bearing phases in controlling carbonate formation remains poorly constrained. This study investigates CO₂ mineralization during hydrothermal interaction between high-Ti Paraná flood basalt and CO₂-charged synthetic seawater under controlled batch reactor conditions (150 °C, 70 bar, up to 30 days), with solid and fluid phases monitored at 5, 10, 20, and 30 days. Siderite (FeCO₃) forms as the dominant precipitated carbonate phase and primary CO₂ sink, co-precipitating with dolomite (MgCa(CO₃)₂) and poorly ordered magnesite (MgCO₃), gypsum (CaSO₄·2H₂O), and amorphous silica, as confirmed by XRD and SEM/EDS analyses. Progressive dissolution of Fe-bearing silicates, particularly pyroxenes, releases Fe²⁺ to solution, promoting siderite precipitation. This carbonate phase consumes the dissolved Fe from ~400 ppm to below detection limit within 30 days. Carbonate precipitation becomes evident between days 20 and 30, as reflected by the decline in dissolved Mg and alkalinity alongside a systematic increase in loss on ignition from −0.01 to +2.41 wt.% over the experimental duration. In parallel, titanomagnetite undergoes low-temperature oxidative alteration, converting Fe²⁺ to Fe³⁺ and limiting Fe availability for carbonate formation, a redox competition that potentially creates favorable conditions for H₂ generation during water–rock interaction. Taken together, these findings indicate that iron redox partitioning is a key control on carbonation efficiency in the High-Ti Paraná system, with broader implications for CO₂ storage potential in iron-rich flood basalt provinces.

As Europe's largest CO₂ emitter, Germany bears a particular responsibility for mitigating its environmental impact. With the amendment of the German Carbon Dioxide Storage Act, industrial-scale offshore and onshore CO₂ storage projects can now be licensed. However, onshore storage must be permitted by the respective federal state, which retains the authority to ban CO₂ storage within its territory. The development of onshore storage facilities therefore remains uncertain, but before committing to exporting most of its captured CO₂ abroad, Germany should thoroughly evaluate its domestic storage options. While the sedimentary rocks of the North German Basin host the largest capacities, alternative methods such as CO₂ mineralisation in mafic and ultramafic rocks may be locally available.

This study experimentally investigates the CO₂ mineralisation potential of selected German igneous rocks. Five lithologies from the Vogelsberg, Eifel, and Harz mountains were subjected to batch reactor experiments to assess their ability to supply divalent metal cations (Ca²⁺, Mg²⁺, Fe²⁺) necessary for permanent CO₂ sequestration through carbonate mineralisation.

Results demonstrate that the tested volcanic and plutonic rocks are chemically suited for CO₂ sequestration. However, significant practical limitations exist. Most magmatic rock complexes in Germany are spatially confined, offering only limited storage volumes. Additionally, CO₂ must be injected in dissolved form, creating substantial water demand in regions where the hydraulic budget is already stressed and restrictions apply due to drinking water protection areas. Combined with expensive reservoir development for limited capacity, these constraints suggest that CO₂ mineralisation in German igneous rocks is unlikely to represent a viable large-scale solution.